656213215561 has 4 divisors (see below), whose sum is σ = 656357474500. Its totient is φ = 656068956624.

The previous prime is 656213215549. The next prime is 656213215571. The reversal of 656213215561 is 165512312656.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 259116631225 + 397096584336 = 509035^2 + 630156^2 .

It is a cyclic number.

It is not a de Polignac number, because 656213215561 - 2⁵ = 656213215529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (656213215571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 72122646 + ... + 72131743.

It is an arithmetic number, because the mean of its divisors is an integer number (164089368625).

Almost surely, 2^656213215561 is an apocalyptic number.

It is an amenable number.

656213215561 is a deficient number, since it is larger than the sum of its proper divisors (144258939).

656213215561 is a wasteful number, since it uses less digits than its factorization.

656213215561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 144258938.

The product of its digits is 324000, while the sum is 43.

The spelling of 656213215561 in words is "six hundred fifty-six billion, two hundred thirteen million, two hundred fifteen thousand, five hundred sixty-one".